Thymosin Alpha-1
CLINICAL USEImmunomodulatory peptide | Zadaxin
By the INFOPEPTIDOS editorial team · content based on scientific literature.
Updated: August 2026.
Key points
- What it is: immunomodulatory peptide derived from a thymic hormone (marketed as Zadaxin).
- Main use: modulating and strengthening the immune system.
- Typical dose: 1.6 mg, twice a week, subcutaneous injection.
- Key result: enhances the T-lymphocyte response without over-activating the system.
- Common effects: well tolerated; mild injection-site discomfort.
- Comparison: immune-focused; used as support in infections and as an adjuvant.
- Status: approved in many countries; not FDA-approved.
Technical data: Molecular formula C129H215N33O55 · Molecular weight 3108.3 g/mol. Source: PubChem.
Overview
What is Thymosin Alpha-1?
Thymosin Alpha-1 is a peptide derived from a hormone produced by the thymus, the gland that 'educates' the immune system. Marketed as Zadaxin and approved in many countries, it is used to modulate immunity in chronic infections, as a vaccine adjuvant and in general immune support.
Key benefits
It strengthens and balances the immune response, supporting the maturation and activity of T lymphocytes. It is researched and used in chronic viral infections (such as hepatitis), sepsis and as immune support, with very good tolerance.
Mechanism of action
It acts on the maturation of T lymphocytes and on dendritic cells, improving pathogen recognition and modulating the immune and inflammatory response without causing uncontrolled over-activation.
Quick start guide
Dosing protocol
| Phase | Dose | Frequency | Duration |
|---|---|---|---|
| Standard | 1.6 mg | 2 times/week (SC) | In cycles |
Subcutaneous route. In some clinical protocols the frequency is higher. The specific dose must be assessed by a healthcare professional.
Reconstitution: units in the syringe
Example with a 10 mg vial + 2 ml of bacteriostatic water → a 5 mg/ml solution. On a U-100 insulin syringe (100 units = 1 ml):
| Dose | Volume | Units (U-100) |
|---|---|---|
| 1.6 mg | 0.32 ml | 32 U |
Is your vial or water different? Calculate the exact units below.
🧮 Calculate your exact syringe dose →⚠️ Who should NOT use it
- People with autoimmune disease or a transplant — consult first (it modulates immunity).
- Pregnancy or breastfeeding.
- Planned immunosuppression — assess with the doctor.
- Always under the supervision of a healthcare professional.
What to expect
- Week 1-2: no striking changes; gradual immune action.
- Week 2-4: possible better response to infections.
- Week 4-8: more consolidated immune support.
- In cycles: adjusted to the clinical goal.
- Side effects: minimal; mild injection discomfort.
- Most effective for: immune support and chronic infections.
Side effects & safety
- Very well tolerated in general.
- Mild discomfort or redness at the injection site.
- Rarely, transient fatigue.
- Caution in autoimmune disease.
- Assess in people with a transplant or immunosuppression.
- Allergic reaction: rash, itching or swelling.
- Flare of an autoimmune disease.
- Marked fever or malaise.
- Any striking, persistent symptom.
- If you are pregnant or planning a pregnancy.
Frequently asked questions
What is Thymosin Alpha-1?
It is an immunomodulatory peptide (Zadaxin) that strengthens and balances the immune system.
What is Thymosin Alpha-1 used for?
For immune support, chronic viral infections and as a vaccine adjuvant.
What is the Thymosin Alpha-1 dose?
Typically 1.6 mg twice a week subcutaneously. The regimen is set by a professional.
How does Thymosin Alpha-1 work?
It supports T-lymphocyte maturation and improves pathogen recognition without over-activating immunity.
What are the side effects?
It is usually very well tolerated; caution in autoimmune diseases.
Is Thymosin Alpha-1 approved?
It is approved in many countries (Zadaxin), but not by the US FDA.
Research areas
- Immune modulation
- Chronic infections
- Vaccine adjuvant
- Recovery
- General health
Related peptides
- TB-500 — Thymosin beta-4 fragment for tissue repair.
- KPV — Anti-inflammatory tripeptide.
- Epitalon — Pineal longevity tetrapeptide.
Related articles
Related topics
- Thymosin Alpha-1 and immunity
- Thymosin Alpha-1 dose
- Thymosin Alpha-1 Zadaxin
- Thymosin Alpha-1 infections
- Thymosin Alpha-1 cycle
- Thymosin Alpha-1 side effects
Summary
What it is: Immunomodulatory peptide (Zadaxin).
How it is researched: Subcutaneous, 1.6 mg twice a week.
Key features: Strengthens and balances immunity. Approved outside the US, not by the FDA.
Related peptides: TB-500, KPV and Epitalon.
References
- Ancell CD et al. (2001). Thymosin alpha-1. Am J Health Syst Pharm. PubMed · DOI
- Simonova MA et al. (2025). Aging and Thymosin Alpha-1. Int J Mol Sci. PubMed · DOI
- Wei Y et al. (2023). Thymosin α-1 in cancer therapy: Immunoregulation and potential applications. Int Immunopharmacol. PubMed · DOI
- Wei YT et al. (2022). Thymosin α-1 Reverses M2 Polarization of Tumor-Associated Macrophages during Efferocytosis. Cancer Res. PubMed · DOI
Studies compiled from PubMed for informational purposes; many are preclinical or research-stage and do not constitute medical advice.